新疆天山山区禾本科牧草物候区域差异及其驱动力分析

Regional differences of gramineae herbage phenology and its driving forces in Tianshan Mountains, Xinjiang

天山山区地形复杂,同种植被因所处地理位置、地形特征的不同,其生育期对气候变化的响应特征差异明显。基于天山山区1990-2015年气象及物候观测数据,利用数理统计及空间插值等方法,分析了典型禾本科牧草物候空间差异及其关键驱动因子,结果表明:(1)26年来,天山山区年平均气温和年平均0 cm地温明显上升,北坡升温幅度大于南坡;年降水量增加,大致为"北坡趋多,南坡趋少";气候总体呈明显暖湿化趋势。(2)天山山区4个牧业气象观测站所共有的优势禾本科牧草物候呈现较明显的差异,春季返青期普遍提前,黄枯期大多为提前,生长季变化差异较大。(3)返青期主要受温度影响,与当月及春季平均气温、平均0 cm地温显著负相关,春季平均温度每升高1℃,返青日期提前1.98-5.77 d,春季平均0 cm地温每升高1℃,返青日期提前1.40-5.08 d;黄枯期主要受前期气温、0 cm地温和降水的综合影响,与前三个月的气温、0 cm地温显著负相关,与降水显著正相关。(4)在热量条件适合时,降水增加,对牧草的生育期是促进作用,相反,若热量条件不足时,降水增加,则会对牧草的发育产生抑制作用。(5)牧草生育期对于海拔高度的敏感性存在明显差异,随海拔高度的增加,物候对气候变化的响应程度更为显著。

The Tianshan Mountains have very complex topographies and the response characteristics of the same kind of vegetation to climate change during its growth period are greatly different as the result of different geographical locations and topographic features.In this study,we analyzed the spatial differences of typical gramineae herbage phenology and the key driving forces by using the meteorological and phenological observation data collected from 1990 to 2015 as well as the mathematical statistics and spatial interpolation methods.The results showed that:(1)During the 26 years,the annual mean temperature and annual mean 0 cm earth temperature increased significantly,and the warming range in the north slope of Tianshan Mountains was greater than that in the south slope.In addition,the annual precipitation varied,roughly being"north slope more,south slope less".Thus,the climate in this region generally showed a warm and humid trend.(2)The phenology of dominant gramineae herbage shared by the four agrometeorological stations in the region of Tianshan Mountains had different features.Generally,the spring greenup date of gramineae herbage started earlier than before,so did its wilting period.Great changes were found in the growth season of the gramineae herbage.(3)The greenup date showed a clear negative correlation with the mean temperatures and mean 0 cm earth temperatures in the current month and spring.For every 1℃rose in the spring mean temperature,the greenup date was 1.98-5.77 d earlier;for every 1℃rose in the spring 0 cm earth temperature,the greenup date was 1.40-5.08 d in advance.The dominant factors that affected the wilting dates jointly were the temperature,0 cm earth temperature and precipitation in the previous three months,which means that the wilting period had an obviously negative correlation with the temperature and 0 cm earth temperature,but a clearly positive correlation with precipitation.(4)The increase of precipitation could promote the growth stage of gramineae herbage when the heat condition was suitable;on the contrary,the increase of precipitation could inhibit the growth stage of the herbage if the heat was insufficient.(5)There was a significant difference in the sensitivity of the herbage growth period to elevation.With the increase of elevation,the response of phenology to climate change was more noticeable.